The long term goal of the proposed research is to define the organization and interrelationships between those components of the central autonomic nervous system which are involved in the control of the circulation. This entails: 1) development of a wiring diagram depicting the specific connections of those neuronal elements which form central cardiovascular circuits; 2) study of the relationships between electrical activity and functional output of these circuits; 3) elucidation of those mechanisms controlling transmission in each of the parallel circuits which may exist; and 4) identification of the synaptic mediators within these circuits which are known to affect transmission of impulses in central cardiovascular pathways.